The present invention relates to an epitaxial growth system used in the steps in manufacturing a semiconductor device and, more particularly, to an exhaust apparatus.
In a conventional epitaxial growth system, reaction gases such as AsH.sub.3 (arsine), PH.sub.3 (phosphine), SiH.sub.4 (silane), and H.sub.2 (hydrogen) are supplied to a reaction furnace, and a semiconductor wafer (to be referred to as a wafer hereinafter) is heated by induction heating or resistive heating to thermally decompose the supplied gases, thereby growing a thin film having a predetermined composition on the wafer. Products and non-reacted gases which are not used for growing the thin film on the wafer are exhausted from the reaction furnace through an exhaust pipe.
In order to trap the products or the like in the exhaust pipe, the exhaust pipe has a dust filter consisting of a metal mesh, a Teflon filter, or the like.
In the conventional exhaust apparatus of the epitaxial growth system, small reaction product particles and non-reacted gases are not sufficiently trapped. For this reason, these products flow in a rotary pump arranged near the distal end of the exhaust pipe to degrade exhausting ability. In addition, arsenic or phosphorus flows into the rotary pump, problems in maintenance or safety are posed. For example, when phosphorus is mixed with oil of the rotary pump, the oil is burnt in the air. Furthermore, when reaction products adhere to the inner portion of a pressure adjusting valve arranged near the distal end of the exhaust pipe, a degree of opening/closing the valve is changed during a pressure adjusting operation to degrade pressure control accuracy. When the size of the mesh in the dust filter is decreased (50 .mu.m or less) to trap small reaction product particles, the exhausting ability is degraded.